A pilot’s latest testimony indicated that a mechanical problem could be to blame for the Boeing 777 passenger jet’s crash landing in San Francisco over the weekend that killed two passengers and injured 180 others on board.

According to a briefing by the U.S. National Transportation Safety Board on Tuesday (Washington time), the captain of the Asiana Airlines flight told NTSB investigators that the automatic throttle system was not maintaining the speed at which he had thought it was programmed.

The investigators are looking into why the plane was flying slower than required, which led the airplane’s tail to strike a seawall at the head of the runway.

The U.S. aviation safety authorities have seemingly focused on a possible pilot error in its investigation into the cause of the crash landing.

Asked if the auto-throttle system was malfunctioning, NTSB chairwoman Deborah Hersman declined to comment, saying it is something investigators are looking into as they examine hundreds of parameters of data downloaded from the plane’s flight data recorders.

In Seoul on Wednesday, Choi Jeong-ho, a senior official from South Korea’s Transport Ministry, confirmed the switches for both the autopilot and auto-throttle systems were still in armed positions.

Choi, head of the ministry’s aviation policy bureau, however, said the failure of the automatic throttle system needs to be confirmed through an analysis of the flight data recorder, which may take weeks or even months.

The ministry said a joint analysis of the flight data recorders from the crashed jet began earlier in the day (Korea time) after two South Korean investigators arrived in Washington.

Industry watchers noted the past record of aviation accidents involving Boeing 777. On Monday, a San Francisco-bound Boeing 777 operated by Japan Airlines turned back to Tokyo after its crew detected a leak in the hydraulic system that controls its flaps, the carrier said. The incident came just three days after the Asiana Airlines 777 crashed in San Francisco on Saturday.

The JAL jetliner, carrying 236 passengers, returned to Tokyo’s Haneda airport three hours and 20 minutes after it departed. Maintenance engineers were investigating the cause of the leak, a spokesman for the Japanese flag carrier said.

Meanwhile, amid a flood of speculations regarding the cause of the crash landing, the NTSB faced criticism that its overly detailed releases related to the accident are hindering the investigation.

The Washington-based Air Line Pilots Association claimed in a statement Tuesday that federal investigators are releasing too much information about the crash of the Boeing 777 that carried 307 people.

The reaction came after the NTSB strongly suggested pilot error as a likely cause of the accident in its Monday briefing.

The statement said, “ALPA is stunned by the amount of detailed operational data from on-board recorders released by the NTSB this soon into the investigation.’’

State-level efforts were made to minimize the aftermath. President Park Geun-hye sent a message to U.S. President Barack Obama over the crash, expressing sympathy to the victims and promising to do whatever it takes to normalize the situation as soon as possible, her spokeswoman Kim Haing said Wednesday.

In the message sent Tuesday evening, Park called the crash truly regrettable, offered sympathy to the victims, and expressed gratitude for U.S. efforts to cope with its aftermath, including a joint probe to determine what caused the crash, Kim said.